[Google Scholar] More-precise Decided Date for cases

Added new logic for scrapeCase(...)/getDate(...) to get and save a more precise Decided Date than what is available in the citelet (if the new logic can find one). Added test case descriptions for all test cases. Added six test cases specifically for testing the added logic.

Also included comment about how the code did and still does fail for a specific case. Included link to Zotero Forum post where this was reported. (https://forums.zotero.org/discussion/44849/zotero-wont-save-google-scholar-case-but-no-error-report-id-949790485/)